def curve_pre():
    a = 25  #将固定参数隐藏在一个函数内部（闭包=函数+环境变量）
    b = 10
    c = 5
    def curve(x):
        return a*x**2+b+c
    return curve

a = 10
f = curve_pre()
print(f.__closure__[0].cell_contents)
print(f.__closure__[1].cell_contents)
print(f.__closure__[2].cell_contents)
print(f(3))
